Symptoms of Pythium root dysfunction, caused by Pythium volutum, may be expressed this time of year during dry, warm, and/or windy days. This is especially true for newer putting greens or those with low organic matter. Patch type symptoms are typical, however ring type symptoms have been observed.
This pathogen infected your root system last fall and it's those affected plants that will be the first to exhibit symptoms of stress from drought, nutrient deficiency, etc. Observing these patches now doesn't necessarily mean that the pathogen is currently active, however it does mean that you will have to battle this disease in late spring/early summer if you don't take preventative measures once the daily mean soil temperatures reach 50 degrees Fahrenheit this spring.
For more information about PRD, please visit : http://www.turffiles.ncsu.edu/diseases/pythium-root-dysfunction